Hoist for microphone dolly and the like



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Feb. 27, 1962 i 04 kEsrec roe J. L. FISHER HOIST FOR MICROPHONE DOLLY AND THE LIKE Filed Sept. 29, 1958 Al-[F/LTEIQ K 100 P2555025 GUAGE 2 Sheets-Sheet 1 INVENTOR. JAMES L. fi/sHze [for/z 167 Feb. 27, 1962 J. L. FISHER HOIST FOR MICROPHONE DOLLY AND THE LIKE 2 Sheets-Sheet 2 Filed Sept. 29, 1958 INVENTOR. (Luv/5 Z. fisf/ae ftowz e "-1 IIIIIIIIL L.

tates This invention relates generally to so-called dollies which are used in the motion picture and television fields as movable supports for various types of equipment, such as microphone booms. The invention deals more particularly with an improved platform hoist for such a dolly.

In motion picture and television work, it is necessary for certain types of equipment to be moved from placeto-place during the filming or televising of a scene. For example, a microphone for picking up an actors speech must always be located in close proximity to the actor and yet be out of the held of view of the television or motion picture camera.

For this reason, a microphone of this type is generally supported at the end of a so-called microphone boom. This boom may be raised, lowered, and turned about a vertical axis to permit limited movement of the microphone with the actor. In order to enable the microphone to follow more extensive movement of the actor, the microphone boom is mounted on a dolly which may be wheeled and steered to follow the actors movements. Preferably, for reasons of more rapid and optimum placement of the microphone, the microphone boom is adjusted by a technician riding directlyon the dolly.

A wide latitude of microphone placement, of course, is permitted by the adjustments of the microphone boom and movement of the dolly. In many cases, however, it is highly desirable or necessary to vary the overall elevation of the boom. Most efiicient adjustment of the boom, in such cases, requires that the boom operating technician be supported on a platform which raises and lowers with the boom. 7

With the foregoing preliminary discussion in mind, a broad object of the invention may be stated as being the provision of a new and improved hoist for dollies of the character described.

A more specific object of the invention is the provision of a hoist of the character described which may be selectively raised and lowered as well as locked in any elevated position by operation of a single control handle.

Another object of the invention is the provision of a hoist of the character described wherein a control handle is carried on a horizontal body supporting platform which raises and lowers with the hoist.

Yet another object of the invention is the provision of a hoist of the character described wherein the hydraulic system for operating the hoist is automatically shut off upon the hoist being elevated to a predetermined position.

A further object of the invention is the provision of the hoist of the character described which is ideally suited for use on microphone dollies and the like.

Yet a further object of the invention is the provision of a novel control mechanism for a hoist of the character described.

Other objects, advantages and features of the invention will become readily apparent as the description proceeds.

Briefly, these objects are attained by the provision of a hydraulic hoist equipped with a cylinder which may be mounted on a microphone dolly, for example, and a piston having a rod which projects above the upper end of the cylinder. This piston rod is connected to a horizontal body supporting platform which is slidably guided on the cylinder.

Movably mounted on the platform is a control handle which is linked to both the control valve of the hydraulic system for operating the hoist and a brake for locking 3,622,901 Patented Feb. 27., 1962 the hoist in any elevated position. The hoist is elevated by movement of this handle in one direction from a neutral position and lowered by movement of the handle in the other direction from the neutral position. The brake of the hoist is engaged when the control handle'is in its neutral position and is released upon movement of the control handle in either direction. I

The linkage connecting the control handle, which is carried on the elevatable platform, and the hydraulic control valve, which is stationarily mounted on the dolly frame, for example, is so designed that elevation of the hoist to a predetermined position automatically closes the eontrol'valve. Excessive elevation of the hoist is thus prevented.

A better understanding of the invention may be had from the following detailed description thereof taken in connection with the annexed drawings, wherein:

FIG. 1 is a perspective view of the present hoist mounted on a dolly;

FIG. 2 is a schematic illustration of the hydraulic system for the hoist;

FIG. 2a is an enlarged detail, partially broken away, of the piston in the hoist of FIG. 2;

FIG. 3 is an enlarged detail, partially in section, illustrating the novel brake and hydraulic control valve operating mechanism of the invention;

FIG. 4 is a side view of the structure shown in FIG. 3;

FIG. 5 is a section taken along line 55 of FIG. 3;

FIG. 6 is an enlarged section taken along line 66 of FIG. 3; and

FIG. 7 is a section taken along line 7-7 of FIG. 3.

Referring now to FIG. 1 of these drawings, the hoist of this invention is generally designated by the numeral 29. Hoist 20 is illustratively mounted on a three wheeled dolly 22 of the character disclosed in my copending ap plication, Serial No. 764,187, filed Sept. 29, 1958, and entitled Steering Mechanism for Microphone Dolly and the Like, now Patent No. 2,950,121.

Hoist 20 comprises a lower vertical cylinder 24. The lower end of this cylinder is rigidly fixed to a horizontal supporting plate 26. Plate 26 is firmly attached, in any convenient manner, to the frame of the dolly 22. Reinforcing rods 28 are connected between the dolly 22 and cylinder 24 for stabilizing the latter.

As shown most clearly in FIG. 2, cylinder 24 comprises an outer sleeve 30 and an inner sleeve or cylinder 32. 0pposite ends of these sleeves are closed by upper and lower end walls 34 and 36, respectively.

Vertically movable in the inner cylinder 32 is a piston 38. This piston has a piston rod 40. Piston rod 40* is slidable inthe upper end wall 34 and extends a substantial distance above the upper end of the cylinder 24.

In one illustrative use of the hoist, a microphone boom 44 is hingeably mounted on the upper end of the piston rod 40. As preliminarily discussed, this microphone boom is adjusted by a technician. Indicated at 46 is a horizontal body supporting platform on which the technicianmay stand. If desired, a seat 48may also be carried on this platform.

Platform 4.6 is rigidly connected to the upper end of the piston rod 40 by a connection 50. This connection is shown as comprising a vertical shaft paralleling the piston rod and secured at its upper end to the rod and at its lower end to the platform 46.

Platform 46, adjacent its forward edge, has an opening in which is located a sleeve bearing 52. Sleeve bearing S2. is slidably received on the outer sleeve 30 of the cylinderld. Welded to the underside of the platform 46 and the bearing sleeve 52 are four diagonal gussets 54 which rigidly secure the sleeve to the platform. Platform 46 is, therefore, slidably supported on the cylinder 24.

The upper and lower ends of the bearing sleeve 52 are neutral position of FIG. 3.

axially and circumferentially slotted, as shown, to form I a pair of cylindric split sleeve sections or friction brake elements 56. One end of these elements is rigidly joined to the bearing sleeve, as may be 'most readily observed in FIG. 5. Welded to the free ends of the elements 56 are radial lugs 58.

Friction brake elements 56 form part of a friction brake 60 for locking the platform 46 in any vertical position on the cylinder 24.

Indicated at 62 is a pressure bar of the brake 6%. Opposite endsof this bar are aligned with the brake element lugs 58. These ends of the pressure bar carry adjustable set screws or pressure feet 64 which engage the lugs 58.

An intermediate point of the pressure bar 62 is pivotally connected, by a pair of links 66, to a short, lateral arm 68 rigid on the lower end of a control handle 70. This lower end of the control handle is pivoted at 72 to the bearing sleeve 52.. As shown most clearly in FIG. 4, the control handle 70 is offset to one side of the pressure bar 62 so as to clear the latter.

It will be apparent from the drawings that the links 66 and control handle arm 68 form, in effect, a toggle linkage. This toggle linkage occupies its dead center position when the control handle '76 is in its vertical or When the control handle 70 is rocked in either direction from its neutral position, the toggle linkage acts to move the pressure feet 64 of the pressure bar 62 away from the brake element lugs '58. Similarly, when the control handle 70 is rocked in either direction back to its neutral position, the pressure feet 64 are moved toward lugs 58.

Indicated at 74 is an L-shaped torsion bar. Leg 76 of this bar is coaxial with control handle pivot 72. The free end of this leg is secured, against twisting, to the underside of the platform 46 by any suitable means, such as illustrated at 78. The other leg S of the torsion bar 74 extends longitudinally of the control handle '76. This .latter end of the torsion bar is locked, by set screws 82, in a sleeve 84 whichis rigidly fixed to a lower longitudinal extension 86 on the control handle 70.

Torsion bar 74 is unstressed when the control handle 70 is in its neutral position of FIG. 3. When the control handle is rocked in either direction from this neutral position, the horizontal leg 76 of the torsion bar is .twisted. This twisting of the bar creates a torsional strain which acts in a direction to bias the control handle 70 to its neutral position.

The pressure feet 64 on the pressure bar 62 are so adjusted that when the control handle 70 is in its neutral position, they press against the lugs 58 so as to urge the brake elements 56 into tight frictional contact with the cylinder 24. Platform 46 is thereby blocked :against vertical movement on the cylinder. control handle is rocked in either direction from its When the neutral position, pressure bar 62 is pulled away from the lugs 58 to relieve the pressure on the brake elements 56. The friction brake is thereby released to permit free vertical movement of the platform 46.

. Hoist 20 is operated by a hydraulic system generally indicated by the numeral 88 in FIG. 1. Referring to the schematic diagram of FIG. '2, this hydraulic system will be seen to comprise a closed system. The annular space 90 between the outer sleeve 30 and the inner cylinder sleeve 32 of the cylinder 24 contains hydraulic fluid 92 and serves as a hydraulic fluid reservoir of the hydraulic system 88. The suction side of a manually operable pump 94 is connected with this reservoir through a hydraulic line 96 and a passage 98 in the lower cylinder end wall 36. A filter 100 is connected in the line 96.

The discharge side of the pump 94 is connected by a line 102 to a four-way coupling or junction 104. Also connected to this junction are an accumulator 166 and a pressure gage 108. The remaining opening in the junction 104 is connected via an hydraulic line 110 to a three-way control valve 112. An hydraulic restrictor 114 is connected in the line 110.

In the solid line position of the control valve 112, hydraulic line 110 is connected to a line 116 which opens through the lower end of the cylinder sleeve 32. In the dotted line position of the control valve 112, line 116 is connected to a line 118 which opens to the lower end of the hydraulic fluid reservoir 90. The control valve has a third closed position, indicated in phantom lines, in which all three lines 110, 116 and 118 are closed. This closed position of the valve will be seen to be located intermediate its two solid line and dotted line open positions.

In operation of the hydraulic system, control valve 112 is placed in its closed position and the hand pump 94 s operated to pump hydraulic fluid 92 from the reservo1r 9% to the accumulator 166. When the control valve is subsequently moved to its solid line open position, the ac cumulator 166 acts to force, hydraulic fluid through the line 11%} into the lower end of the cylinder sleeve 32 to move the piston 38, platform 46 and microphone boom 44 upwardly as a unit. When these parts attain the desired elevation, control valve 112 is closed. Subsequent lowering of the hoist is accomplished by placing the control valve 112 in its dotted line open position. In this position of the control valve, the elevatable parts of the hoist descend under their own weight and that of an operator on the platform 46, hydraulic fluid being displaced from the lower end of the cylinder sleeve 32 through lines 116 and 118 into the reservoir 90.

Control valve 112 is fixedly mounted on the hoist supporting plate 26 and rotates about a vertical axis. Fixed in any suitable manner to the lower end of the bearing sleeve 52, in vertical alignment with the control valve 112, is a bearing block 126. This bearing block has a bore 122 coaxial with the turning axis of the valve 112. Iournalled in this bore is a sleeve 124-. The upper end of sleeve 124 is rigidly fixed to one end of a horizontal arm 126 having a circular opening 123 aligned with the opening in the of parallel pins 134 which are slidably engageable with opposite side faces of the valve stem 132. Arm 126 is, therefore, slidably keyed to the valve stem.

Pivotally connected at one end to the free end of the arm 126 is a link 136. The other end of link 136 is connected by a ball and socket coupling 138 to the lower end of the control handle extension 86.

It will be seen, therefore, that rocking of the control handle 70 to the left, as it is viewed in FIG. 3, turns the control valve 112 in a counterclockwise direction as the valve is viewed from the top. Similarly, rocking of the control handle to the right turns the control valve in a clockwise direction. The parts are arranged in such a way that when the control handle 70 is in its neutral positionof FIG. 3, the control valve 112 occupies its phantom line closed position of FIG. 2. Rocking of the control handle 70 to the left turns the control valve in a counterclockwise direction from this closed position to its solid line open position of FIG. 2 to cause raising of the hoist. Rocking of the control handle to the right of its neutral position turns the control valve in a clockwise direction from its closed position to its dotted line open position to eifect a lowering of the hoist.

From the description thus far, it will be apparent that when the control handle 76 is in its neutral position, the brake 60 is engaged to lock the platform 46 in its current elevated position and the control valve is closed so as to render the hydraulic system 88 inoperative. Rocking of the control handle 70 to the left of its neutral position,

as the handle is viewed in FIG. 3, simultaneously releases the brake 60 and sets the control valve for elevating the hoist. Similarly, rocking of the control handle 70 to the right of its neutral position simultaneously releases the brake 60 and sets the control valve for lowering of the hoist. Thus, a technician on the platform 46 may raise, lower or lock the platform 46 in fixed position by appropriate operation of the control handle.

In order to prevent excessive elevation of the hoist, means are provided for automatically returning the control valve 112 to its closed position from its solid line open position when the platform 46 is raised to a predetermined elevation. To this end, the upper end of the valve stem 132 is helically twisted in a counterclockwise direction as the stem is viewed from its upper end. The angle through which the stem is twisted corresponds to the angle through which the control valve 112 is turned between its solid line open position and phantom line closed position of FIG. 2.

In operation, when the control handle 7i) is pulled to the left to rotate the control valve to its solid line open position and cause elevating of the hoist, the keys or pins 134 on the valve operating arm 126 slide upwardly along the valve stem. Should the operator fail to release the control handle, riding of the keys 134 onto the helically twisted portion 149 of the valve stem produces a clockwise torque on the latter which turns the control valve from its solid line open position to its phantom line closed position to shut oif the hoist. Thus, elevation of the hoist is automatically terminated upon the platfonn reaching a predetermined height.

Operation of the invention will be apparent from the preceding description. Thus, movement of the control handle 76 in one direction or the other from its neutral position, by an operator on thepl-atform 46, simultaneously releases the brake 60 and operates the hydraulic system 38 to cause raising or lowering of the platform, as the case may be. When the control handle is released, the torsion bar 74 automatically returns the control handle to its neutral position to shut ofi the hydraulic system and engage the brake. Should the operator fail to release the control handle from its left hand, elevating position upon the platform reaching a predetermined height, the control valve 112 is automatically returned to its closed position to shut off the hydraulic system.

In order to prevent trapping of air below the piston 38, the lower face of the latter has a bore in which is press-fitted a porous bronze bushing or slug 38a (FIG. 2a). A passage 38b in the piston communicates the upper end of the piston bore with the cylinder space above the piston. The porous bronze bushing material from which the slug 38a is made has numerous minute passages through which air below the piston may leak to the cylinder space above the piston and then to the exterior of the cylinder 32 through vent ports 32a adjacent the upper end of the cylinder.

A small amount of hydraulic fluid will leak through the slug 32a, of course. Since the rate of this fluid leakage is extremely slight and the platform is mechanically clamped in a fixed vertical position, the presence of the leakage path through the piston does not interfere with the operation of the hoist.

It will be apparent, therefore, that there has been decribed and illustrated a hoist which is fully capable of attaining the several objects and advantages preliminarily set forth. While a preferred embodiment of the invention has been disclosed, it will be obvious that-numerous modifications in design, arrangement of parts and instrumentalities are possible Within the scope of the following claims.

I claim:

1. In a device of the character described, a support, an upright hydraulic cylinder rigidly mounted on said support, a piston movable in said cylinder and including a piston rod extending above the cylinder, a hydraulic system on said support fluidly connected to said cylinder for raising and lowering said piston in the cylinder, said hydraulic system including a control valve on said support including a long rotatable valve stem extending up wardly along said cylinder, a platform fixed to said piston rod, a movable control handle on said platform, link means connected to said handle and slidably keyed to said valve stem for turning of the latter by movement of said handle, said handle being movable to one position to turn said valve stem to a first position for elevating said piston and to another position to turn said control valve stem to a second position for stopping said piston, and the upper end of said valve stem being helically twisted to causeturning of the valve stemfrom said first position to said second position upon predetermined elevation of said piston with said handle in said one position. 2. In a device of the character described, a support, an upright hydraulic cylinder rigidly mounted on said support, a piston movable in said cylinder and including a piston rod extending above the cylinder, a hydraulic system on said support fluidly connected to said cylinder for raising and lowering said piston in the cylinder, said by draulic system including a control valve on said support including a long rotatable valve stem extending upwardly along said cylinder, a platform fixed to said piston rod, a movable control handle on said platform, link means connected to said handle and slidably keyed to said valve stem for turning of the latter by movement of said handle, said handle having a neutral position wherein said piston is held stationary and being movable in one direction from said neutral position to elevate said piston and in the opposite direction to lower said piston, releasable rake means on said platform engageable with said cylinder for locking said piston in fixed vertical position, and

means connected between said handle and brake means for engaging the latter when said handle is in neutral position and releasing said brake means upon movement of said handle in either direction from the neutral position.

3. In a hydraulically operated device, a pair of relatively movable parts, means for effecting relative movement between the parts including a hydraulic cylinder mounted on one part, a piston mounted on the other part and movable in the cylinder, and a hydraulic fluid supply system connected to the cylinder having a valve means for controlling flow of hydraulic fluid to and from the cylinder, a rod member having a rectangular cross section carried on one part and extending parallel to the direction of relativemovement of said parts, a slide member carried on the other part and having a rectangular opening slidably receiving the rod member, whereby said members undergo relative movement along the. longitudinal axis of the rod member during relative movement of said parts, one of said members being rotatable'on said longitudinal axis, means for restraining the other member against rotation on said longitudinal axis, said rod member having a helically twisted portion for causing rotation of said one member upon predetermined relative movement of the parts, and a connection between said one member and valve means whereby the latter is operated by rotation of said one member.

4. :In a hydraulically operated device, a pair of relatively movable parts, means for effecting relative movement between the parts including a hydraulic cylinder mounted on one part, a piston mounted on the other part and movable in the cylinder, and a hydraulic fluid supply system having a valve means for controlling flow of hydraulic fluid to and from the cylinder, a rod member carried on one part and extending parallel to the direction of relative movement of said parts, a slide member carried on the other part and having an opening slidably and non-rotatably receiving the rod member, whereby said members undergo rel-ative movement along the longitudinal axis of the rod member during relative movement of said parts, one of said members being rotatable on said axis, manually operable means on the part carry to rotate said one one ember on said axis, coacting means on said members to rotate said one member on said axis upon predetermined relative movement of said parts when said other member is restrained against rotation, and a connection between said one member and valve means ,whereby the latter is operated by rotation of said one member.

5. A hydraulic hoist, comprising a supporting base, a vertically movable'hydraulic hoist means on the base including a vertical cylinder part and a piston part movable in the cylinder part, means rigidly mounting one of said parts on said base, whereby the other part is vertically movable with respect to the base, a hydraulic sys- '*tem connected to the cylinder for effecting raising and lowering of the movable part, a bearing sleeve rigidly mounted on one part and slidable along the other part during movement of the vertically movable part, said sleeve having a circumferentially extending slit adjacent each end and an axial slit at each end extending from one end of the adjacent circumferential slit through the adjacent end of the sleeve whereby to define a radially flexible, friction brake element at each end of the sleeve, a lug on the free end of each brake element extending radially beyond the outer surface of the sleeve, a brake operating handle pivoted on the sleeve between the ends thereof, a pressure bar extending between and engageable .at its ends with said lugs, link means connecting the brake handle and pressure bar for urging the latter against said lugs to force the brake elements into frictional contact with the part on which the bearing sleeve slides when said handle occupies a given normal position, whereby to lock the movable part against movement, and said handle being swingable from said normal position to relieve the pressure of said pressure bar on said brake elements and thereby release said movable part for movement.

'6. The subject matter of claim 5 including spring means for urging said brake handle to normal position.

7. The subject matter of claim 5 wherein said brake handle is swingable in opposite directions from normal position to release said brake elements for permitting movement of the movable part, said hydraulic system including a control valve having a closed position and which is turnable in one direction from said closed position to a first open position to effect raising of the movable part and in the opposite direction from said closed position to a second open position to efiect lowering of the movable part, and means operatively connecting the brake handle and valve so that the latter occupies its closed position in the normal position of the handle and is turned to one open position by movement of the handle in one direction from its normal position and to the other open position by movement of the handle in the other direction from its normal position.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain Nov. 7, 

